The “unforgettable” Grand European cruise a Westchester couple took for their 30th wedding anniversary turned into the trip from hell.

The husband and wife slapped Viking Cruises with a $5 million class action lawsuit claiming the company knew its ship was “plagued with electrical problems” before a breakdown that forced guests to be bused around to dreary destinations.

Manhattan attorney James P. Cinque and his wife Marie-Helene Cinque booked their two week jaunt aboard the Viking Magni for Sept. 24 through Oct. 8.

The Viking Cruises brochure boasted an “unforgettable” trip along a “stunning stretch” of the Rhine River with “friendly, attentive, award-winning service,” according the Manhattan civil suit.

But the cruise line allegedly hid from its passengers that the Viking Magni had suffered power issues during the prior cruise.

Ten days into the Cinque’s voyage the electrical system failed again.

“The boat limped into the closest port” and when it could not be fixed, the 200 passengers were loaded onto cramped buses for seven-hour trips between stops, according to court papers.

“The boat shouldn’t have broken down,” James told The Post in an interview.

“It’s not like it was an act of God,” he said.

When the James, 62, and Marie-Helene, 58, asked for a refund and to leave the group, they were told they would have to do so at their own expense.

“We were taken to Frankfurt instead of the beautiful cities along the river,” James said.

“We spent one whole day on the bus. We missed Amsterdam entirely,” he griped.

The attorney said he only filed the suit after all the arguments with Vikings’ customer service reps got him was a 50 percent credit for a future trip.

“I don’t want to go back on one of their cruises. It was horrible,” James said.